This application requests funds for the completion of a case-control study of childhood rhabdomyosarcoma (RMS). The major goal of this collaborative national study is to investigate potentially etiologic envvironmental factors. We will evaluate the following hypotheses: fathers' but not mothers' cigarette smoking is a strong risk factor for RMS; there is an inverse relationship between a child's immunization status and RMS risk and a positive association between RMS and preventable infectious diseases; environmental exposures to chemicals, mother's ae at subject's birth, and family history of asthma are risk factors for RMS; and there is an inverse association between RMS and socioeconomic status. These hypotheses evolved from the findings of our first case-control study of childhood RMS. We will refine and reevaluate these hypotheses, assess the role of other environmental agents, and also investigate the possible role of heredity as suggested by reports of familial aggregation of RMS with other soft tissue sarcomas and breast cancer. We have developed new methods for the utilization of subjects from collaborative cancer clinical trials for etiologic research. Our approach can greatly facilitate studies of both rare and common tumors by permitting rapid accrual of sufficient numbers of subjects. At the same time, it fosters greater interaction between epidemiologists and clinicians. Our study taps the resources of a collaborative clinical trials group for a case-control study which focuses on etiologic factors. The Intergroup Rhabdomyosarcoma Study (IRS), which serves as our means of identifying cases, obtains subjects from two large cooperative groups (the Pediatric Oncology Group and the Children's Cancer Study Group). Approximately 80% of all new cases in the United States are entered on IRS protocols each year and all diagnoses are subjected to central expert pathology review. We expect to accrue a total of 350 new cases from over 70 medical centers. Controls come from the same communities as cases and are of the same race and sex and of similar age. One control for each case is identified by random-digit dialing, and all subjects' parents are interviewed by telephone. We believe that the issue of environmental factors in the etiology of childhood cancers has not been adequately explored. The relatively short induction periods between potential etiologic exposures and disease manifestation in children provide unique opportunities for the study of environmental etiologic agents. Through this study of RMS, we hope to generate new hypotheses about the etiology of childhood cancer in general.